Techniques for uplink transmission management

ABSTRACT

Techniques for uplink transmission management in a wireless communications system are described herein. An example method may include receiving an explicit uplink grant that indicates one or more implicit uplink grants. In an aspect, the example method may include performing a first clear channel assessment (CCA) in response to the explicit uplink grant in a first time slot. In another aspect, the example method may include, if the first CCA fails, sequentially performing one or more additional CCAs respectively in one or more time slots subsequent to the first time slot in response to the one or more implicit uplink grants, and transmitting the PDU over the unlicensed or shared spectrum and in a time slot subsequent to the time slot in which one of the one or more additional CCAs succeeds.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a Divisional of and claims the benefit ofU.S. patent application Ser. No. 15/153,656, entitled “TECHNIQUES FORUPLINK TRANSMISSION MANAGEMENT,” filed May 12, 2016, which claims thebenefit of U.S. Provisional Application Ser. No. 62/161,839, entitled“TECHNIQUES FOR UPLINK TRANSMISSION MANAGEMENT,” filed May 14, 2015, thecontents of which are both incorporated by reference in theirentireties.

BACKGROUND

The described aspects relate generally to wireless communicationsystems. More particularly, the described aspects relate to techniquesfor uplink transmission management in wireless communications.

Wireless communications systems are widely deployed to provide varioustypes of communication content such as voice, video, packet data,messaging, broadcast, and so on. These systems may be multiple-accesssystems capable of supporting communication with multiple users bysharing the available system resources (e.g., time, frequency, andpower). Examples of such multiple-access systems include code divisionmultiple access (CDMA) systems, time division multiple access (TDMA)systems, frequency division multiple access (FDMA) systems,single-carrier frequency division multiple access (SC-FDMA) systems,time division synchronous code division multiple access (TD-SCDMA)systems, and orthogonal frequency division multiple access (OFDMA)systems.

These multiple-access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent wireless devices to communicate on a municipal, national,regional, and even global level. An example telecommunication standardis Long Term Evolution (LTE). LTE is a set of enhancements to theUniversal Mobile Telecommunications System (UMTS) mobile standardpromulgated by Third Generation Partnership Project (3GPP). LTE isdesigned to support mobile broadband access through improved spectralefficiency, lowered costs, and improved services using OFDMA on thedownlink, SC-FDMA on the uplink, and multiple-input multiple-output(MIMO) antenna technology. However, as the demand for mobile broadbandaccess continues to increase, there exists a need for furtherimprovements in LTE technology. These improvements may also beapplicable to other multi-access technologies and the telecommunicationstandards that employ these technologies.

By way of example, a wireless multiple-access communications system mayinclude a number of base stations, each simultaneously supportingcommunication for multiple communication devices, which may be otherwiseknown as user equipment (UEs), wireless devices, mobile devices orstations (STAs). A base station may communicate with the communicationdevices on downlink channels (e.g., for transmissions from a basestation to a UE) and uplink channels (e.g., for transmissions from a UEto a base station).

As cellular networks have become more congested, operators are beginningto look at ways to maximize the use of available network resources. Oneapproach may include utilizing an unlicensed or shared spectrum (e.g., 5Giga Hertz (GHz) band) to schedule traffic between the base station andthe one or more communication devices. As referenced herein, a wirelesscommunications system that adapts LTE air interface to operate inunlicensed or shared spectrum may be referred to as an LTE-U system or alicense-assisted access (LAA) system. The unlicensed spectrum may beemployed by cellular systems in different ways. For example, in somesystems, the unlicensed spectrum may be employed in a standaloneconfiguration, with all carriers operating exclusively in an unlicensedportion of the wireless spectrum (e.g., LTE Standalone). In othersystems, the unlicensed spectrum may be employed in a manner that issupplemental to licensed band operation by utilizing one or moreunlicensed carriers operating in the unlicensed portion of the wirelessspectrum in conjunction with an anchor licensed carrier operating in thelicensed portion of the wireless spectrum (e.g., LTE SupplementalDownLink (SDL)).

Due to respective requirements regarding operations in licensed spectrumand unlicensed or shared spectrum, uplink transmissions are generallysubject to a listen-before-talk (LBT) approach. That is, when acommunication device (e.g., UE or STA) has uplink data for transmission,the communication device may perform a channel check (e.g., clearchannel assessment (CCA) or extended clear channel assessment (eCCA))prior to transmitting any data on the uplink channel. If the result ofthe channel check indicates that a channel is available for the uplinktransmission, i.e., the channel is clear for use and the channel checksucceeds, the communication device may then accordingly transmit uplinkdata. However, if the result of the channel check indicates that thechannel is unavailable for the uplink transmission, i.e., the channel iscurrently busy and the channel check fails, the communication devicetypically may have to wait until some later time resulting in uplinktransmission delays. Other aspects of operations in licensed spectrumand unlicensed or shared spectrum that may cause delays in uplinktransmissions are related to the use of hybrid automatic repeat request(HARD) operations.

Therefore, there is a need to provide mechanisms for uplink transmissionmanagement that are suitable for wireless communications in anunlicensed or shared spectrum.

SUMMARY

The following presents a simplified summary of one or more aspects inorder to provide a basic understanding of such aspects. This summary isnot an extensive overview of all contemplated aspects, and is intendedto neither identify key or critical elements of all aspects nordelineate the scope of any or all aspects. Its sole purpose is topresent some concepts of one or more aspects in a simplified form as aprelude to the more detailed description that is presented later.

The present disclosure presents examples of techniques for configuring awindow size. In an aspect of the disclosure, an example method formanaging uplink transmissions in a license-assisted access (LAA) systemmay include receiving an explicit uplink grant that indicates one ormore implicit uplink grants. In another aspect, the example method mayinclude performing a first clear channel assessment (CCA) in response tothe explicit uplink grant in a first time slot. In an aspect, theexample method may include, if the first CCA succeeds, transmitting aprotocol data unit (PDU) over an unlicensed or shared spectrum and in atime slot subsequent to the first time slot. In another aspect, theexample method may include, if the first CCA fails, sequentiallyperforming one or more additional CCAs respectively in one or more timeslots subsequent to the first time slot in response to the one or moreimplicit uplink grants.

In another aspect, an example method for managing uplink transmissionsin an LAA system may include receiving an explicit uplink grant thatindicates one or more implicit uplink grants. In an aspect, the examplemethod may include performing a first clear channel assessment (CCA) inresponse to the explicit uplink grant in a first time slot. In anotheraspect, the example method may include, if the first CCA succeeds,respectively transmitting over an unlicensed or shared spectrum copiesof a protocol data unit (PDU) in time slots immediately subsequent tothe first time slot, wherein a number of transmitted copies of the PDUis based at least in part on the one or more implicit uplink grants.

In an aspect, an example method for managing uplink transmissions in anLAA system may include receiving a first explicit uplink grant fortransmission of a first protocol data unit (PDU) associated with a firstHybrid Automatic Repeat Request (HARQ) process and receiving a secondexplicit uplink grant for transmission of a second PDU associated with asecond HARQ process, the second explicit uplink grant being receivedsubsequent to the first explicit uplink grant. In another aspect, theexample method may include performing a first clear channel assessment(CCA) in response to the first explicit uplink grant in a first timeslot and performing a second CCA in response to the second explicituplink grant in a second time slot. In another aspect, the examplemethod may include, if the first CCA fails and the second CCA succeeds,determining whether to transmit over an unlicensed or shared spectrumthe first PDU or the second PDU in a time slot subsequent to the secondtime slot in association with the second HARQ process.

To the accomplishment of the foregoing and related ends, the one or moreaspects comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative featuresof the one or more aspects. These features are indicative, however, ofbut a few of the various ways in which the principles of various aspectsmay be employed, and this description is intended to include all suchaspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosed aspects will hereinafter be described in conjunction withthe appended drawings, provided to illustrate and not to limit thedisclosed aspects, wherein like designations denote like elements, andin which:

FIG. 1 is a diagram illustrating an example of a wireless communicationsystem in which uplink transmission management may be performed;

FIG. 2A is a diagram illustrating an example of components of thewireless communication system for uplink grant and transmissionmanagement;

FIG. 2B is a diagram illustrating an example of components of a networkentity (e.g., base station or access point) in the wirelesscommunication system for uplink grant management;

FIG. 2C is a diagram illustrating an example of components of a mobiledevice (e.g., user equipment) in the wireless communication system foruplink transmission management;

FIG. 3 is a diagram illustrating an example of sub-components of thewireless communication system for uplink transmission management;

FIG. 4A is a diagram illustrating an example of conventional operationsregarding uplink transmissions;

FIG. 4B is a diagram illustrating another example of conventionaloperations regarding uplink transmissions;

FIG. 5A, is a diagram illustrating an example of operations of uplinktransmission management;

FIG. 5B is a diagram illustrating another example of operations ofuplink transmission management;

FIG. 6 is a diagram illustrating yet another example of operations ofuplink transmission management;

FIG. 7 is a flowchart illustrating an example of a method for uplinktransmission management in an LAA system;

FIG. 8 is a flowchart illustrating an example of another method foruplink transmission management in an LAA system;

FIG. 9 is a flowchart illustrating an example of yet another method foruplink transmission management in an LAA system;

FIG. 10 is a diagram illustrating an example of a hardwareimplementation for an apparatus employing a processing system; and

FIG. 11 is a diagram illustrating an example of a network entity (e.g.,a base station or an access point) in communication with a UE in atelecommunication system having aspects configured for uplinktransmission management.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various configurations and isnot intended to represent the only configurations in which the conceptsdescribed herein may be practiced. The detailed description includesspecific details for the purpose of providing a thorough understandingof various concepts. However, it will be apparent to those skilled inthe art that these concepts may be practiced without these specificdetails. In some instances, well known structures and components areshown in block diagram form in order to avoid obscuring such concepts.

Several aspects of telecommunication systems will now be presented withreference to various apparatus and methods. These apparatus and methodswill be described in the following detailed description and illustratedin the accompanying drawings by various blocks, components, circuits,processes, algorithms, etc. (collectively referred to as “elements”).These elements may be implemented using electronic hardware, computersoftware, or any combination thereof. Whether such elements areimplemented as hardware or software depends upon the particularapplication and design constraints imposed on the overall system.

By way of example, an element, or any portion of an element, or anycombination of elements may be implemented as a “processing system” thatincludes one or more processors. Examples of processors includemicroprocessors, microcontrollers, graphics processing units (GPUs),central processing units (CPUs), application processors, digital signalprocessors (DSPs), reduced instruction set computing (RISC) processors,systems on a chip (SoC), baseband processors, field programmable gatearrays (FPGAs), programmable logic devices (PLDs), state machines, gatedlogic, discrete hardware circuits, and other suitable hardwareconfigured to perform the various functionality described throughoutthis disclosure. One or more processors in the processing system mayexecute software. Software shall be construed broadly to meaninstructions, instruction sets, code, code segments, program code,programs, subprograms, software components, applications, softwareapplications, software packages, routines, subroutines, objects,executables, threads of execution, procedures, functions, etc., whetherreferred to as software, firmware, middleware, microcode, hardwaredescription language, or otherwise.

Various aspects are now described with reference to the drawings. In thefollowing description, for purposes of explanation, numerous specificdetails are set forth in order to provide a thorough understanding ofone or more aspects. It may be evident, however, that such aspect(s) maybe practiced without these specific details.

As discussed above, congestion on the traditional licensed band (e.g.,2.4 GHz band) has motivated network operators to offload wireless widearea network (WWAN) traffic to the unlicensed or shared spectrum (e.g.,5 GHz band) in order to meet the ever-growing bandwidth demands. In LTEsystems over unlicensed spectrum (LTE-U) or LAA systems, uplinktransmissions from a UE to a network entity (e.g., eNodeB) are subjectto listen-before-talk (LBT) principle. In an aspect, the UE may have toperform a channel check before transmitting data on the uplink channel.When the channel check fails, unnecessary delays may occur since the UEmay have to wait for a subsequent uplink grant for transmitting thedata. In some other examples, the data transmitted on the uplink datamay be out of order.

Thus, in one aspect, a network entity may be configured to include,indicate, or specify one or more implicit uplink grants in an explicituplink grant. That is, when a UE receives the explicit uplink grant anda first channel check fails, the UE may perform another channel check asif the UE received more than one explicit uplink grant. As referencedherein, a channel check may refer to an operation to determine if achannel is available for transmitting data. As such, the UE may not haveto wait for the network entity to transmit another explicit uplink grantseveral time slots later that may cause delays in uplink transmissions.Further, in another aspect, when the UE receives the explicit uplinkgrant with the implicit uplink grants includes therein, the UE may beconfigured to transmit one or more copies of the data (e.g., transmitcopies with different redundancy information) on the uplink such thatthe delay caused by possible retransmission may be mitigated.

In another aspect, when a first data unit, such as a protocol data unit(PDU) is blocked from being transmitted (e.g., transmission of the PDUdoes not occur) due to a failed channel check, the UE may be configuredto transmit the first PDU when the UE receives a subsequent uplink grantfor a second PDU. As such, a first PDU in time may be transmitted beforeother PDUs.

FIG. 1 illustrates an example of a wireless communications system 100 inwhich techniques for uplink transmission management may be performed inaccordance with various aspects of the present disclosure. The wirelesscommunications system 100 includes base stations 105, small cell accesspoints (AP) 120, mobile devices 115, and a core network 130. In someaspects of the present disclosure, the base station 105 may be referredto as a macro cell base station, and AP 120 may be referred to as smallcell base station. The base station 105 and the AP 120 may be generallyreferred to as network entities as they are configured to providenetwork access to the mobile devices 115. One or more mobile devices 115may include an uplink transmission manager component 201 configured tomanage uplink transmissions, as described further herein. On the otherside, one or more network entities (base stations 105 by way of example)may include an uplink grant manager component 211 configured to generateor manage explicit uplink grant, or implicit uplink grant, or both. Thecore network 130 may provide user authentication, access authorization,tracking, internet protocol (IP) connectivity, and other access,routing, or mobility functions. The base stations 105 may interface withthe core network 130 through backhaul links 132 (e.g., S1, etc.). Thebase stations 105 and AP 120 may perform radio configuration andscheduling for communication with the mobile devices 115, or may operateunder the control of a base station controller (not shown). In variousexamples, the base station 105 and AP 120 may communicate, eitherdirectly or indirectly (e.g., through core network 130), with each otherover backhaul links 134 (e.g., X2, Over-the-air (OTA) etc.), which maybe wired or wireless communication links. In some aspects of the presentdisclosure, the base station 105 and AP 120 may share their respectivetiming parameters associated with communication scheduling.

The base station 105 and AP 120 may wirelessly communicate with themobile device 115 via one or more antennas. Each of the base station 105and AP 120 may provide communication coverage for a respectivegeographic coverage area 110. In some examples, base station 105 may bereferred to as a base transceiver station, a radio base station, anaccess point, a radio transceiver, a NodeB, eNodeB (eNB), Home NodeB, aHome eNodeB, or some other suitable terminology. The geographic coveragearea 110-a for a base station 105 and coverage area 110-b for AP 120 maybe divided into sectors making up only a portion of the coverage area(not shown). The wireless communications system 100 may include basestation 105 and AP 120 of different types (e.g., macro or small cellbase stations). There may be overlapping geographic coverage areas 110for different technologies.

While the mobile devices 115 may communicate with each other through thebase station 105 and AP 120 using communication links 125, each mobiledevice 115 may also communicate directly with one or more other mobiledevices 115 via a direct wireless link 135. Two or more mobile devices115 may communicate via a direct wireless link 135 when both mobiledevices 115 are in the geographic coverage area 110 or when one or moremobile devices 115 are within the AP geographic coverage area 110-b.Examples of direct wireless link 135 may include Wi-Fi Directconnections, connections established using a Wi-Fi Tunneled Direct LinkSetup (TDLS) link, and other P2P group connections. In otherimplementations, other peer-to-peer connections or ad hoc networks maybe implemented within the wireless communications system 100.

In some examples, the wireless communications system 100 includes awireless wide area network (WWAN) such as an LTE/LTE-Advanced (LTE-A)network. WWAN technologies such as LTE or LTE-A may be adapted foroperation over an unlicensed or shared spectrum. In LTE/LTE-A networks,the term evolved node B (eNB) may be generally used to describe the basestations 105, while the term user equipment (UEs) or wireless devicesmay be generally used to describe the mobile devices 115. The wirelesscommunications system 100 may include a heterogeneous LTE/LTE-A networkin which different types of eNBs provide coverage for variousgeographical regions. The wireless communications system 100 may alsosupport eCC operations, which may use listen-before-talk (LBT) like LTEover unlicensed spectrum, but may have a different numerology than LTEover unlicensed spectrum.

The wireless communications system 100 may, in some examples, alsosupport a wireless local area network (WLAN). A WLAN may be a networkemploying techniques based on the Institute of Electrical andElectronics Engineers (IEEE) 802.11x family of standards (“Wi-Fi”). Insome examples, each eNB or base station 105 and AP 120 may providecommunication coverage for a macro cell, a small cell, or other types ofcell. The term “cell” is a 3GPP term that may be used to describe a basestation, a carrier or component carrier associated with a base station,or a coverage area (e.g., sector, etc.) of a carrier or base station,depending on context.

A macro cell generally covers a relatively large geographic area (e.g.,several kilometers in radius) and may allow unrestricted access bymobile device 115 with service subscriptions with the network provider.A small cell is a lower-powered base station, as compared with a macrocell, that may operate in the same or different (e.g., licensed,unlicensed, etc.) frequency bands as macro cells. Small cells mayinclude pico cells, femto cells, and micro cells according to variousexamples. A pico cell, for example, may cover a small geographic areaand may allow unrestricted access by mobile device 115 with servicesubscriptions with the network provider. A femto cell may also cover asmall geographic area (e.g., a home) and may provide restricted accessby mobile device 115 having an association with the femto cell (e.g.,mobile device 115 in a closed subscriber group (CSG), mobile device 115for users in the home, and the like). An eNB for a macro cell may bereferred to as a macro eNB. An eNB for a small cell may be referred toas a small cell eNB, a pico eNB, a femto eNB, or a home eNB. An eNB maysupport one or multiple (e.g., two, three, four, and the like) cells(e.g., component carriers). In some aspects of the present disclosure,the base station 105 may be referred to as a macro cell base station,and AP 120 may be referred to as small cell base station.

The wireless communications system 100 may support synchronous orasynchronous operation. For synchronous operation, the base stations 105may have similar frame timing, and transmissions from different basestations 105 may be approximately aligned in time. For asynchronousoperation, the base stations 105 may have different frame timing, andtransmissions from different base stations 105 may not be aligned intime. The techniques described herein may be used for either synchronousor asynchronous operations.

The communication networks that may accommodate some of the variousdisclosed examples may be packet-based networks that operate accordingto a layered protocol stack. In the user plane, communications at thebearer or packet data convergence protocol (PDCP) layer may be IP-based.A radio link control (RLC) layer may perform packet segmentation andreassembly to communicate over logical channels. A medium access control(MAC) layer may perform priority handling and multiplexing of logicalchannels into transport channels. The MAC layer may also use hybridautomatic repeat request (HARD) to provide retransmission at the MAClayer to improve link efficiency. In the control plane, the radioresource control (RRC) protocol layer may provide establishment,configuration, and maintenance of an RRC connection between a mobiledevice 115 and the base stations 105. The RRC protocol layer may also beused for core network 130 support of radio bearers for the user planedata. At the physical (PHY) layer, the transport channels may be mappedto physical channels.

The mobile devices 115 may be dispersed throughout the wirelesscommunications system 100, and each mobile device 115 may be stationaryor mobile. A mobile device 115 may also include or be referred to bythose skilled in the art as a user equipment (UE), mobile station, asubscriber station, STA, a mobile unit, a subscriber unit, a wirelessunit, a remote unit, a mobile device, a wireless device, a wirelesscommunications device, a remote device, a mobile subscriber station, anaccess terminal, a mobile terminal, a wireless terminal, a remoteterminal, a handset, a user agent, a mobile client, a client, or someother suitable terminology. A mobile device 115 may be a cellular phone,a personal digital assistant (PDA), a wireless modem, a wirelesscommunication device, a handheld device, a tablet computer, a laptopcomputer, a cordless phone, a wireless local loop (WLL) station, or thelike. A mobile device may be able to communicate with various types ofbase stations and network equipment including macro eNBs, small celleNBs, relay base stations, and the like. In some examples, a dual-radioUE 115-a, may include a WLAN radio (not shown) and a WWAN radio (notshown) that may be configured to concurrently communicate with basestation 105 (using the WWAN radio) and with AP 120 (using the WLANradio).

The communication links 125 shown in wireless communications system 100may include uplink (UL) transmissions from a mobile device 115 to a basestation 105 or AP 120, or downlink (DL) transmissions, from a basestation 105 or AP 120 to a mobile device 115. The downlink transmissionsmay also be called forward link transmissions while the uplinktransmissions may also be called reverse link transmissions. Eachcommunication links 125 may include one or more carriers, where eachcarrier may be a signal made up of multiple sub-carriers (e.g., waveformsignals of different frequencies) modulated according to the variousradio technologies described above. Each modulated signal may be sent ona different sub-carrier and may carry control information (e.g.,reference signals, control channels, etc.), overhead information, userdata, etc. The communication links 125 may transmit bidirectionalcommunications using frequency division duplex (FDD) (e.g., using pairedspectrum resources) or time division duplex (TDD) operation (e.g., usingunpaired spectrum resources). Frame structures may be defined for FDD(e.g., frame structure type 1) and TDD (e.g., frame structure type 2).

The communication links 125 may utilize resources of licensed spectrumor unlicensed spectrum, or both. Broadly speaking, the unlicensedspectrum in some jurisdictions may range from 600 Megahertz (MHz) to 6Gigahertz (GHz), but need not be limited to that range. As used herein,the term “unlicensed spectrum” or “shared spectrum” may thus refer toindustrial, scientific and medical (ISM) radio bands, irrespective ofthe frequency of those bands. An “unlicensed spectrum” or “sharedspectrum” may refer to a spectrum used in a contention-basedcommunications system. In addition, the term “licensed spectrum” or“cellular spectrum” may be used herein to refer to wireless spectrumutilized by wireless network operators under administrative license froma governing agency.

Wireless communications system 100 may also support operation onmultiple cells or carriers, a feature which may be referred to ascarrier aggregation (CA) or multi-carrier operation. A carrier may alsobe referred to as a component carrier (CC), a layer, a channel, etc. Theterms “carrier,” “component carrier,” “cell,” and “channel” may be usedinterchangeably herein. A mobile device 115 may be configured withmultiple downlink CCs and one or more uplink CCs for carrieraggregation. Carrier aggregation may be used with both FDD and TDDcomponent carriers.

FIG. 2A is a diagram illustrating example components of the wirelesscommunication system for uplink grant and transmission management. Asdepicted, UE 115 may be in communication with a network entity 220associated with core network 130 via a primary cell 205 and/or an LAAsecondary cell 203. In some examples, network entity 220 may be referredto as a base station, a base transceiver station, an access point, aradio transceiver, a NodeB, eNodeB (eNB), Home NodeB, a Home eNodeB, orsome other suitable terminology. In some aspects, primary cell 205 mayrefer to connectivity services provided in a licensed spectrum and LAAsecondary cell 203 may refer to connectivity services provided in anunlicensed spectrum. UE 115 may receive signaling, including uplinkgrants, via primary cell 205 and transmit data (e.g., PDUs) via LAAsecondary cell 203.

Further, UE 115 may be configured to execute an uplink transmissionmanager component 201 that includes a grant receiver 202, a channelexaminer 204, a data transmitter 206, a buffer manager 208, and atransmission determiner 210. Network entity 220 may be configured toexecute an uplink grant manager component 211 to generate an explicituplink grant 212 and at least one implicit uplink grant 214.

In one aspect, uplink grant manager component 211 may generate explicituplink grant 212 that indicates, when received by UE 115, UE 115 isauthorized to transmit an amount of data on the uplink. Explicit uplinkgrant 212 may also include a maximum size of the data authorized totransmit on the uplink. In addition to generating explicit uplink grant212, uplink grant manage process 211 may further include, or otherwiseindicate, one or more implicit uplink grants 214 in explicit uplinkgrant 212. In other words, each of the implicit uplink grants 214 mayauthorize UE 115 to transmit the amount of data on the uplink. Uplinkgrant manager component 211 may determine a count of implicit uplinkgrants 214 based on factors including a total number of UEs within thecoverage of wireless communications system 100.

In another aspect, when explicit uplink grant 212 is received by grantreceiver 202 of UE 115 at a time slot n via primary cell 205, channelexaminer 204 may perform a channel check prior to transmitting the dataon the uplink channel. If the channel check succeeds, i.e., an uplinkchannel is available for transmitting the data, data transmitter 206 maytransmit the data on the uplink channel via LAA secondary cell 203. Ifthe channel check fails, i.e., the uplink channel is not available fortransmitting the data, buffer manager 208 may store the data, e.g., afirst PDU, in a HARQ buffer associated with a HARQ process, e.g., HARQbuffer 207. Further, transmission determiner 210 may determine whichdata should be transmitted if one or more PDUs have been stored in theHARQ buffer due to previous failed channel checks. Such determinationmay be performed based on one or more factors further described in FIG.3. In addition, other aspects of the components of network entity 220and UE 115 are described in details in accordance with FIG. 2B and FIG.2C, respectively.

Referring to FIG. 2B, in an aspect, a network entity 220 (e.g., a basestation or an access point) associated with core network 130 may be incommunication with UE 115 via a primary cell 205 and/or an LAA secondarycell 203. In some aspects, primary cell 205 may refer to connectivityservices provided in a licensed spectrum and LAA secondary cell 203 mayrefer to connectivity services provided in an unlicensed spectrum.Network entity 220 may transmit signaling, including uplink grants, viaprimary cell 205 and receive data (e.g., PDUs) via LAA secondary cell203.

In an aspect, network entity 220 may include one or more antennas 222,RF front end 224 and transceiver 226 for receiving and transmittingradio transmissions, including, for example, the described signalingmessages and also any messages corresponding to uplink grant and/oruplink transmission management. RF front end 224 may be connected to theone or more antennas 222. RF front end 224 may include, for example, oneor more low-noise amplifiers (LNAs) (not shown), one or more switches(not shown), one or more power amplifiers (PAs) (not shown), and one ormore filters (not shown) for transmitting and receiving RF signals onthe uplink channels and downlink channels. RF front end 224 is merely anexample configuration; in an aspect, other configurations for RF frontend 224 may be used by network entity 220. In an aspect, components ofRF front end 224 may connect with transceiver 226. Transceiver 226 mayconnect to one or more processor 230.

In another aspect, network entity 220 may include one or more processors230 that may operate in combination with uplink grant manager component211, which may generate an explicit uplink grant 212 and/or at least oneimplicit uplink grant 214, for uplink grant and/or uplink transmissionmanagement as described herein. In an aspect, the one or more processors230 may include a modem 232 that uses one or more modem processors. Inanother aspect, the one or more processors 230 may be communicativelycoupled to at least a memory 228, wherein the memory 228 may beconfigured to store instructions for handling uplink grant and/or uplinktransmission management.

Referring to FIG. 2C, in an aspect, an UE 115 may be in communicationwith a network entity 220 associated with core network 130 via a primarycell 205 and/or an LAA secondary cell 203. In some aspects, primary cell205 may refer to connectivity services provided in a licensed spectrumand LAA secondary cell 203 may refer to connectivity services providedin an unlicensed spectrum. UE 115 may receive signaling, includinguplink grants, via primary cell 205, and transmit data (e.g., PDUs) viaLAA secondary cell 203.

In an aspect, UE 115 may include RF front end 223 and transceiver 237for receiving and transmitting radio transmissions, including, forexample, the described signaling messages and also any messagescorresponding to the operation of uplink transmission manager component201. RF front end 223 may be connected to one or more antennas 221. RFfront end 223 may include, for example, one or more low-noise amplifiers(LNAs) 225, one or more switches 227, 229, 235, one or more poweramplifiers (PAs) 233, and one or more filters 231 for transmitting andreceiving RF signals. RF front end 223 is merely an exampleconfiguration; in an aspect, other configurations for RF front end 223may be used by UE 115. In an aspect, components of RF front end 223 mayconnect with transceiver 237. Transceiver 237 may connect to one or moreprocessor 241.

In an aspect, LNA 225 may amplify a received signal at a desired outputlevel. In an aspect, each LNA 225 may have a specified minimum andmaximum gain values. In an aspect, RF front end 223 may use one or moreswitches 227, 229 to select a particular LNA 225 and its specified gainvalue based on a desired gain value for a particular application.

Further, for example, one or more PA(s) 233 may be used by RF front end223 to amplify a signal for an RF output at a desired output powerlevel. In an aspect, each PA 233 may have a specified minimum andmaximum gain values. In an aspect, RF front end 223 may use one or moreswitches 229, 235 to select a particular PA 233 and its specified gainvalue based on a desired gain value for a particular application.

Also, for example, one or more filters 231 may be used by RF front end223 to filter a received signal to obtain an input RF signal. Similarly,in an aspect, for example, a respective filter 231 may be used to filteran output from a respective PA 233 to produce an output signal fortransmission. In an aspect, each filter 231 may be connected to aspecific LNA 225 and/or PA 233. In an aspect, RF front end 223 may useone or more switches 227, 229, 235 to select a transmit or receive pathusing a specified filter 231, LNA 225, and/or PA 233, based on aconfiguration as specified by transceiver 237 and/or processor 241.

In an aspect, UE 115 may include one or more processors 241 that mayoperate in combination with an uplink transmission manager component 201for managing uplink transmissions as described herein. In an aspect,uplink transmission manager component 201 may include a grant receiver202, a channel examiner 204, a data transmitter 206, a buffer manager208, and a transmission determiner 210. In another aspect, buffermanager 208 may be associated with one or more HARQ buffers 207. In anaspect, the one or more processors 241 may include a modem 243 that usesone or more modem processors. In another aspect, the one or moreprocessors 241 may be communicatively coupled to at least a memory 239,wherein the memory 239 may be configured to store instructions forhandling uplink transmission management.

Various functions related to uplink transmission manager component 201may be included in modem 243 and/or one or more processors 241 and, inan aspect, may be executed by a single processor, while in otheraspects, different ones of the functions may be executed by acombination of two or more different processors. For example, in anaspect, the one or more processors 241 may include any one or anycombination of a modem processor, or a baseband processor, or a digitalsignal processor, or a transmit processor, or a transceiver processorassociated with transceiver 237. In particular, the one or moreprocessors 241 may execute functions included in uplink transmissionmanager component 201, including, but not limited to, a grant receiver202, a channel examiner 204, a data transmitter 206, a buffer manager208, and a transmission determiner 210. In an aspect, buffer manager 208may be associated with one or more HARQ buffers 207. In addition, someother aspects of the components of uplink transmission manager component201 are described in greater details in accordance with FIG. 4A, FIG.4B, FIG. 5A, FIG. 5B, and FIG. 6.

FIG. 3 is a diagram illustrating example sub-components of the wirelesscommunication system for uplink transmission management. As depicted,transmission determiner 210 may determine which data to be transmittedon the uplink channel based on time duration 302 and granted size 304.

As referenced herein, time duration 302 may refer to a time periodbetween two consecutive explicit uplink grant. Granted size 304 mayrefer to a size limit indicating a maximum size of data that may betransmitted on the uplink channel in response to an explicit uplinkgrant. Other aspects of the sub-components of transmission determiner210 are described in greater details in accordance with FIG. 4A, FIG.4B, FIG. 5A, FIG. 5B, and FIG. 6.

FIG. 4A is a diagram illustrating an example of conventional operationsregarding uplink transmissions. FIG. 4B is a diagram illustratinganother example of conventional operations regarding uplinktransmissions. For brevity, uplink transmissions are illustrated tooccur immediately subsequent to a succeeded channel check.

For FIG. 4A, a first issue is that the uplink data transmission isdelayed due to a failed channel check. As depicted in FIG. 4A,conventionally, when grant receiver 202 receives explicit uplink grant401 at a time slot n, channel examiner 204 may perform a channel checkprior to transmitting the data. If the channel check fails, e.g., shownas failed CCA 405, data transmitter 206 may not transmit the data on theuplink channel, e.g., shown as blocked UL transmission 406, at time slotn+4 or any other predetermined time slot. Thus, uplink transmissionmanager component 201 may have to wait for another explicit uplink grant212 from network entity 220 to transmit the blocked data. For example,when grant receiver 202 receives another explicit uplink grant 403 attime slot n+8, channel examiner 204 may perform another channel checkprior to transmitting the data. If the channel check succeeds, e.g.,shown as succeeded CCA 407, data transmitter 206 may transmit the data,shown as UL transmission 408, at time slot n+12.

For FIG. 4B, a second issue is that the PDUs transmitted on the uplinkchannel may be out of order. As depicted in FIG. 4B, conventionally,grant receiver 202 may similarly receive an explicit uplink grant 413associated with a first HARQ process from network entity 220. Channelexaminer 204 may also perform a channel check prior to transmitting thedata. If the channel check fails, shown as failed CCA 409, a MAC PDU maybe blocked from transmission, e.g., shown as blocked MAC PDU 410.Blocked MAC PDU 410 may be temporarily stored by buffer manager 208 in aHARQ buffer associated with the first HARQ process waiting to betransmitted in response to a further explicit uplink grant. Meanwhile,grant receiver 202 may receive another explicit uplink grant 415associated with a second HARQ process. Channel examiner 204 mayaccordingly perform a channel check prior to data transmission. If thechannel check succeeds, e.g., shown as succeeded CCA 411, datatransmitter 206 may transmit MAC PDU 412 on the uplink channel. However,the blocked MAC PDU 410 may be a PDU that should be transmitted prior toMAC PDU 412 in time and thus, network entity 220 may have to wait forblocked MAC PDU 410 to be transmitted, even when MAC PDU 412 issuccessfully received, and re-order MAC PDU 412 and blocked MAC PDU 410.

FIG. 5A, is a diagram illustrating an example of operations of uplinktransmission management and FIG. 5B is a diagram illustrating anotherexample of operations of uplink transmission management.

FIG. 5A provides an example approach to address the first issueillustrated in FIG. 4A. As depicted in FIG. 5A, grant receiver 202 mayreceive an explicit uplink grant 501, together with one or more implicituplink grants 503 included therein (shown as two implicit uplink grantsin FIG. 5A), at a time slot n. When a first channel check fails at timeslot n+3 (e.g., one of failed CCAs 502), rather than waiting for anotherexplicit uplink grant at time slot n+8, channel examiner 204 may performone or more additional channel checks at subsequent time slots. Forexample, channel examiner 204 may immediately perform the additionalchannel checks at subsequent time slots n+4 and n+5. A count of theadditional channel checks may equal the count of implicit uplink grants503. If one of the additional channel checks succeeds, data transmitter206 may subsequently transmit the data on the uplink channel. Forexample, an additional channel check may succeed at time slot n+5 (shownas succeeded CCA 504), data transmitter 206 may accordingly transmit thedata on the uplink channel at time slot n+6 (shown as UL transmission506). As such, UE 115 may not have to wait till later time slots, e.g.,time slot n+12 as shown in FIG. 4A, to transmit the data and unnecessarydelay may be mitigated.

In an aspect, if grant receiver 202 receives another explicit uplinkgrant while UE 115 is processing the implicit uplink grants, theexplicit uplink grant may be delayed after the implicit uplink grantsare processed.

Further, each of the explicit or implicit uplink grants may expire aftera predetermine time duration.

FIG. 5B provides another example approach to address the first issueillustrated in FIG. 4A. As depicted in FIG. 5B, grant receiver 202 mayreceive an explicit uplink grant 508, together with one or more implicituplink grants 509 included therein (shown as two implicit uplink grantsin FIG. 5B), at time slot n. Channel examiner 204 may perform a channelcheck at time slot n+3, when the channel check succeeds (shown assucceeded CCA 510), data transmitter 206 may respectively transmitmultiple copies of the data at subsequent time slots, e.g., time slotsn+4, n+5, and n+6. Each copy of the data may be a version of differentredundancy, e.g., including different redundancy information. The countof the copies may be determined based on the count of implicit uplinkgrants 509 and the count of failed channel checks. For example, whengrant receiver 202 receives explicit uplink grant 508 and two implicituplink grants 509 and a first channel check in time succeeds (e.g.,succeeded CCA 510), data transmitter 206 may transmit three copies ofthe data, each in a time slot subsequent to succeeded CCA 510. When thefirst channel check in time fails, channel examiner 204 may perform asecond channel check in a time slot subsequent to the first channelcheck. In some examples, channel examiner 204 may perform a secondchannel check in a time slot immediately subsequent to the first channelcheck If the second channel check succeeds, data transmitter 206 mayonly transmit two copies of the data on the uplink channel.

FIG. 6 provides an example approach to address the second issue in FIG.4B. As depicted in FIG. 6, grant receiver 202 may receive explicituplink grant 602 at time slot n via primary cell 402. Explicit uplinkgrant 602 may indicate that UE 115 is authorized to transmit MAC PDU606, MAC PDU 606 being associated with a first HARQ process. Channelexaminer 204 may perform a channel check at time slot n+3. If thechannel check fails (shown as failed CCA 610), MAC PDU may be blockedfrom being transmitted at time slot n+4 and may be stored in a bufferassociated with the first HARQ process, e.g., HARQ buffer 620. Later intime, grant receiver 202 may receive, at time slot n+4, an explicituplink grant 604 indicating that UE 115 is authorized to transmitanother MAC PDU (not shown) being associated with a second HARQ process.Channel examiner 204 may similarly perform a channel check at time slotn+7. If the channel check succeeds (shown as succeeded CCA 608),transmission determiner 210 may determine whether to transmit MAC PDU606 based on one or more factors including time duration 302, i.e., thetime period between receiving explicit uplink grant 602 and 604, andgranted size 304, i.e., the maximum size of data may be transmitted inaccordance with explicit uplink grant 604. For example, if time duration302 is greater than a predetermine threshold, which indicates that UE115 has sufficient time to perform operations to retrieve MAC PDU 606,transmission determiner 210 may determine to transmit MAC PDU 606,rather than the other MAC PDU originally associated with the second HARQprocess. As another example, if granted size 304 is greater than thesize of MAC PDU 606, transmission determiner 210 may determine totransmit MAC PDU 606 and maybe a portion of the other MAC PDU originallyassociated with the second HARQ process. As such, network entity 220 mayreceive PDUs in a correct order.

In some aspects, prior to transmitting MAC PDU 606, buffer manager 208may move MAC PDU 606 from a HARQ buffer associated with the first HARQprocess, e.g., HARQ buffer 620, to another HARQ buffer associated withthe second HARQ process, e.g., HARQ buffer 622.

In another aspect, if MAC PDU 606 is successfully transmitted on theuplink channel, the buffer that stored MAC PDU 606 at UE 115 may becleared.

FIG. 7 is an example flowchart for uplink transmission management in anLAA system. Method 700 is described below with reference to ones of UEs115 described with reference to FIGS. 1-3.

At 702, method 700 may include grant receiver 202 receiving an explicituplink grant that indicates one or more implicit uplink grants. Forexample, grant receiver 202 may receive an explicit uplink grant 501,together with one or more implicit uplink grants 503 included therein(shown as two implicit uplink grants in FIG. 5A), at a time slot n.

At 704, channel examiner 204 may perform a first clear channelassessment (CCA) in response to the explicit uplink grant in a firsttime slot. For example, channel examiner 204 may perform a channel checkat time slot n+3.

At 706, uplink transmission manager component 201 of UE 115 maydetermine if the first CCA succeeds.

In an aspect, when uplink transmission manager component 201 determinesthat the first CCA succeeds, UE 115 may proceed to 708, and datatransmitter 206 may transmit a PDU over an unlicensed or shared spectrumand in a time slot subsequent to the first time slot. For example, if achannel check succeeds in time slot n+3, data transmitter 206 mayimmediately transmit the data in time slot n+4.

In another aspect, when uplink transmission manager component 201determines that the first CCA does not succeed, UE 115 may proceed to710, and channel examiner 204 may sequentially perform one or moreadditional CCAs respectively in one or more time slots subsequent to thefirst time slot in response to the one or more implicit uplink grants.For example, when a first channel check fails at time slot n+3 (e.g.,one of failed CCAs 502), rather than waiting for another explicit uplinkgrant at time slot n+8, channel examiner 204 may perform one or moreadditional channel checks at time slots n+4 and n+5. A count of theadditional channel checks may equal the count of implicit uplink grants503. If one of the additional channel checks succeeds, data transmitter206 may subsequently transmit the data on the uplink channel. Forexample, an additional channel check may succeed at time slot n+5 (shownas succeeded CCA 504), data transmitter 206 may accordingly transmit thedata on the uplink channel at time slot n+6 (shown as UL transmission506). As such, UE 115 may not have to wait till later time slots, e.g.,time slot n+12, to transmit the data and unnecessary delay may bemitigated.

In another aspect of FIG. 7, an example apparatus for managing uplinktransmissions in a license-assisted access (LAA) system is provided. Inan aspect, the apparatus includes means for receiving an explicit uplinkgrant that indicates one or more implicit uplink grants. In an aspect,the apparatus also includes means for performing a first clear channelassessment (CCA) in response to the explicit uplink grant in a firsttime slot. In another aspect, the apparatus includes means fortransmitting a protocol data unit (PDU) over an unlicensed or sharedspectrum and in a time slot subsequent to the first time slot if thefirst CCA succeeds. In an aspect, the apparatus may also include meansfor sequentially performing, if the first CCA fails, one or moreadditional CCAs respectively in one or more time slots subsequent to thefirst time slot in response to the one or more implicit uplink grants.In another aspect, the apparatus includes means for transmitting the PDUover the unlicensed or shared spectrum and in a time slot subsequent tothe time slot, if the first CCA fails, in which one of the one or moreadditional CCAs succeeds.

In an aspect of FIG. 7, an example computer-readable medium storingcomputer executable code for managing uplink transmissions in alicense-assisted access (LAA) system is provided. In an aspect, thecomputer-readable medium includes computer executable code for receivingan explicit uplink grant that indicates one or more implicit uplinkgrants. In another aspect, the computer-readable medium also includescomputer executable code for performing a first clear channel assessment(CCA) in response to the explicit uplink grant in a first time slot. Inan aspect, the computer-readable medium includes computer executablecode for transmitting a protocol data unit (PDU) over an unlicensed orshared spectrum and in a time slot subsequent to the first time slot ifthe first CCA succeeds. In another aspect, the computer-readable mediumincludes computer executable code for sequentially performing, if thefirst CCA fails, one or more additional CCAs respectively in one or moretime slots subsequent to the first time slot in response to the one ormore implicit uplink grants. In an aspect, the computer-readable mediumincludes computer executable code for transmitting the PDU over theunlicensed or shared spectrum and in a time slot subsequent to the timeslot in which one of the one or more additional CCAs succeeds if thefirst CCA fails.

Still referring FIG. 7, another example apparatus for managing uplinktransmissions in a license-assisted access (LAA) system is provided. Inan aspect, the apparatus may include a memory configured to storeinstructions and at least one processor coupled to the memory, the atleast one processor and the memory are configured to execute theinstructions to perform the following features. In another aspect, theapparatus may include a grant receiver configured to receive an explicituplink grant that indicates one or more implicit uplink grants. In anaspect, the apparatus may include a channel examiner configured toperform a first clear channel assessment (CCA) in response to theexplicit uplink grant in a first time slot. In another aspect, theapparatus may also include a data transmitter configured to transmit aprotocol data unit (PDU) over an unlicensed or shared spectrum and in atime slot subsequent to the first time slot if the first CCA succeeds.In an aspect, if the first CCA fails, the channel examiner included inthe apparatus may be configured to sequentially perform one or moreadditional CCAs respectively in one or more time slots subsequent to thefirst time slot in response to the one or more implicit uplink grants.In another aspect, the data transmitter included in the apparatus may befurther configured to transmit the PDU over the unlicensed or sharedspectrum and in a time slot subsequent to the time slot in which one ofthe one or more additional CCAs succeeds.

FIG. 8 is another example flowchart for uplink transmission managementin an LAA system. Method 800 is described below with reference to onesof UEs 115 described with reference to FIGS. 1-3.

At 802, method 800 may include grant receiver 202 receiving an explicituplink grant that indicates one or more implicit uplink grants. Forexample, grant receiver 202 may receive an explicit uplink grant 508,together with one or more implicit uplink grants 509 included therein(shown as two implicit uplink grants in FIG. 5B), at a time slot n.

At 804, method 800 may include channel examiner 204 performing a firstclear channel assessment (CCA) in response to the explicit uplink grantin a first time slot. For example, channel examiner 204 may perform achannel check at time slot n+3.

At 806, uplink transmission manager component 201 of UE 115 maydetermine if the first CCA succeeds.

In an aspect, when uplink transmission manager component 201 determinesthat the first CCA succeeds, UE 115 may proceed to 808, data transmitter206 may respectively transmit over an unlicensed or shared spectrumcopies of a protocol data unit (PDU) in time slots subsequent to thefirst time slot, wherein a number of transmitted copies of the PDU isbased at least in part on the one or more implicit uplink grants. Forexample, when the channel check succeeds (shown as succeeded CCA 510),data transmitter 206 may respectively transmit multiple copies of thedata at subsequent time slots, e.g., time slots n+4, n+5, and n+6. Eachcopy of the data may be a version of different redundancy, e.g.,including different redundancy information. The count of the copies maybe determined based on the count of implicit uplink grants 509 and thecount of failed channel checks. For example, when grant receiver 202receives explicit uplink grant 508 and two implicit uplink grants 509and a first channel check in time succeeds (e.g., succeeded CCA 510),data transmitter 206 may transmit three copies of the data, each in atime slot subsequent to succeeded CCA 510.

In another aspect, when uplink transmission manager component 201determines that the first CCA does not succeed, UE 115 may proceed to810, and channel examiner 204 may perform an additional CCA subsequentto the first time slot and data transmitter 206 may respectivelytransmit the one or more copies of the PDU in one or more third timeslots subsequent to the additional CCA if the additional CCA succeeds.When the first channel check in time fails, channel examiner 204 mayperform a second channel check in a time slot subsequent to the firstchannel check. If the second channel check succeeds, data transmitter206 may only transmit two copies of the data on the uplink channel intime slots n+5 and n+6.

In another aspect of FIG. 8, an example apparatus for managing uplinktransmissions in a license-assisted access (LAA) system is provided. Inan aspect, the apparatus includes means for receiving an explicit uplinkgrant that indicates one or more implicit uplink grants. In an aspect,the apparatus also includes means for performing a first clear channelassessment (CCA) in response to the explicit uplink grant in a firsttime slot. In another aspect, the apparatus includes means forrespectively transmitting over an unlicensed or shared spectrum copiesof a protocol data unit (PDU), if the first CCA succeeds, in time slotssubsequent to the first time slot, wherein a number of transmittedcopies of the PDU is based at least in part on the one or more implicituplink grants. In an aspect, the apparatus also includes means forperforming an additional CCA in a time slot subsequent to the first timeslot if the first CCA fails. In another aspect, the apparatus includesmeans for respectively transmitting over the unlicensed or sharedspectrum one or more copies of the PDU in one or more time slotssubsequent to a time slot in which the additional CCA succeeds.

In an aspect of FIG. 8, an example computer-readable medium storingcomputer executable code for managing uplink transmissions in alicense-assisted access (LAA) system is provided. In an aspect, thecomputer-readable medium includes computer executable code for receivingan explicit uplink grant that indicates one or more implicit uplinkgrants. In another aspect, the computer-readable medium includescomputer executable code for performing a first clear channel assessment(CCA) in response to the explicit uplink grant in a first time slot. Inan aspect, the computer-readable medium includes computer executablecode for respectively transmitting over an unlicensed or shared spectrumcopies of a protocol data unit (PDU), if the first CCA succeeds, in timeslots subsequent to the first time slot, wherein a number of transmittedcopies of the PDU is based at least in part on the one or more implicituplink grants.

In another aspect, the above mentioned example computer-readable mediummay also include computer executable code for performing an additionalCCA in a time slot subsequent to the first time slot if the first CCAfails. In another aspect, the above mentioned example computer-readablemedium may include computer executable code for respectivelytransmitting over the unlicensed or shared spectrum one or more copiesof the PDU in one or more time slots subsequent to a time slot in whichthe additional CCA succeeds.

FIG. 9 is an example flowchart for uplink transmission management in anLAA system. Method 900 is described below with reference to ones of UEs115 described with reference to FIGS. 1-3.

At 902, method 900 may include grant receiver 202 receiving a firstexplicit uplink grant for transmission of a first PDU associated with afirst HARQ process. For example, grant receiver 202 may receive explicituplink grant 602 at time slot n via primary cell 402. Explicit uplinkgrant 602 may indicate that UE 115 is authorized to transmit MAC PDU606, MAC PDU 606 being associated with a first HARQ process.

At 904, method 900 may include grant receiver 202 receiving a secondexplicit uplink grant for transmission of a second PDU associated with asecond HARQ process, the second explicit uplink grant being receivedsubsequent to the first explicit uplink grant. For example, grantreceiver 202 may receive, at time slot n+4, an explicit uplink grant 604indicating that UE 115 is authorized to transmit another MAC PDU (notshown) being associated with a second HARQ process.

At 906, method 900 may include channel examiner 204 performing a firstclear channel assessment (CCA) in response to the first explicit uplinkgrant in a first time slot. For example, channel examiner 204 mayperform a channel check at time slot n+3.

At 908, method 900 may include channel examiner 204 performing a secondCCA in response to the second explicit uplink grant in a second timeslot. For example, channel examiner 204 may similarly perform a channelcheck at time slot n+7.

At 910, method 900 may include transmission determiner 210 determiningwhether to transmit over an unlicensed or shared spectrum the first PDUor the second PDU in a time slot subsequent to the second time slot inassociation with the second HARQ process if the first CCA fails and thesecond CCA succeeds. For example, with failed CCA 610 and succeeded CCA608, transmission determiner 210 may determine whether to transmit MACPDU 606 based on one or more factors including time duration 302, i.e.,the time period between receiving explicit uplink grant 602 and 604, andgranted size 304, i.e., the maximum size of data may be transmitted inaccordance with explicit uplink grant 604. For example, if time duration302 is greater than a predetermine threshold, which indicates that UE115 has sufficient time to perform operations to retrieve MAC PDU 606,transmission determiner 210 may determine to transmit MAC PDU 606,rather than the other MAC PDU originally associated with the second HARQprocess. As another example, if granted size 304 is greater than thesize of MAC PDU 606, transmission determiner 210 may determine totransmit MAC PDU 606 and maybe a portion of the other MAC PDU originallyassociated with the second HARQ process. As such, network entity 220 mayreceive PDUs in a correct order.

In an aspect, prior to transmitting MAC PDU 606, buffer manager 208 maymove MAC PDU 606 from the buffer associated with the first HARQ processto another buffer associated with the second HARQ process.

In another aspect of FIG. 9, an example apparatus for managing uplinktransmissions in a license-assisted access (LAA) system is provided. Inan aspect, the apparatus includes means for receiving a first explicituplink grant for transmission of a first protocol data unit (PDU)associated with a first Hybrid Automatic Repeat Request (HARQ) process.In an aspect, the apparatus also includes means for receiving a secondexplicit uplink grant for transmission of a second PDU associated with asecond HARQ process, the second explicit uplink grant being receivedsubsequent to the first explicit uplink grant. In another aspect, theapparatus includes means for performing a first clear channel assessment(CCA) in response to the first explicit uplink grant in a first timeslot. In an aspect, the apparatus also includes means for performing asecond CCA in response to the second explicit uplink grant in a secondtime slot. In another aspect, the apparatus includes means fordetermining whether to transmit over an unlicensed or shared spectrumthe first PDU or the second PDU, if the first CCA fails and the secondCCA succeeds, in a time slot subsequent to the second time slot inassociation with the second HARQ process.

Still referring FIG. 9, in another aspect, the above mentioned exampleapparatus may include means for storing the first PDU in a first HARQbuffer associated with the first HARQ process. In an aspect, the abovementioned example apparatus may also include means for moving the firstPDU, in response to a determination being made to transmit the first PDUin association with the second HARQ process, from the first HARQ bufferto a second HARQ buffer associated with the second HARQ process. In anaspect, the above mentioned example apparatus may also include means formoving the second PDU from a MAC buffer to a second HARQ bufferassociated with the second HARQ process in response to a determinationbeing made to transmit the second PDU in association with the secondHARQ process. In another aspect of the above mentioned exampleapparatus, the means for determining whether to transmit over theunlicensed or shared spectrum the first PDU or the second PDU is basedat least in part on a difference in transmission time and/or adifference in size between the first explicit grant and the secondexplicit grant.

In an aspect of FIG. 9, an example computer-readable medium storingcomputer executable code for managing uplink transmissions in alicense-assisted access (LAA) system is provided. In an aspect, thecomputer-readable medium includes computer executable code for receivinga first explicit uplink grant for transmission of a first protocol dataunit (PDU) associated with a first Hybrid Automatic Repeat Request(HARQ) process. In another aspect, the computer-readable medium includescomputer executable code for receiving a second explicit uplink grantfor transmission of a second PDU associated with a second HARQ process,the second explicit uplink grant being received subsequent to the firstexplicit uplink grant. In an aspect, the computer-readable mediumincludes computer executable code for performing a first clear channelassessment (CCA) in response to the first explicit uplink grant in afirst time slot. In another aspect, the computer-readable mediumincludes computer executable code for performing a second CCA inresponse to the second explicit uplink grant in a second time slot. Inan aspect, the computer-readable medium includes computer executablecode for determining to transmit over an unlicensed or shared spectrumthe first PDU or the second PDU, if the first CCA fails and the secondCCA succeeds, in a time slot subsequent to the second time slot inassociation with the second HARQ process.

Still referring FIG. 9, the above mentioned example computer-readablemedium may, in an aspect, include computer executable code for storingthe first PDU in a first HARQ buffer associated with the first HARQprocess. In another aspect, the above mentioned examplecomputer-readable medium may include computer executable code for movingthe first PDU, in response to a determination being made to transmit thefirst PDU in association with the second HARQ process, from the firstHARQ buffer to a second HARQ buffer associated with the second HARQprocess. In an aspect, the above mentioned example computer-readablemedium may also include computer executable code for moving the secondPDU from a MAC buffer to a second HARQ buffer associated with the secondHARQ process in response to a determination being made to transmit thesecond PDU in association with the second HARQ process. In anotheraspect of the above example computer-readable medium, the computerexecutable code for determining whether to transmit over the unlicensedor shared spectrum the first PDU or the second PDU is based at least inpart on a difference in transmission time and/or a difference in sizebetween the first explicit grant and the second explicit grant.

In an aspect of FIG. 9, another example apparatus for managing uplinktransmissions in a license-assisted access (LAA) system is provided. Inan aspect, the apparatus may include a memory configured to storeinstructions and at least one processor coupled to the memory, the atleast one processor and the memory are configured to execute theinstructions to perform the following features. In another aspect, theapparatus may include a grant receiver configured to receive a firstexplicit uplink grant for transmission of a first protocol data unit(PDU)associated with a first Hybrid Automatic Repeat Request (HARQ)process, and receive a second explicit uplink grant for transmission ofa second PDU associated with a second HARQ process, the second explicituplink grant being received subsequent to the first explicit uplinkgrant. In an aspect, the apparatus may include a channel examinerconfigured to perform a first clear channel assessment (CCA) in responseto the first explicit uplink grant in a first time slot, and perform asecond CCA in response to the second explicit uplink grant in a secondtime slot. In an aspect, the apparatus may include a transmissiondeterminer configured to determine whether to transmit over anunlicensed or shared spectrum the first PDU or the second PDU in a timeslot subsequent to the second time slot in association with the secondHARQ process if the first CCA fails and the second CCA succeeds.

Still referring FIG. 9, in an aspect, the above example apparatus mayfurther include a buffer manager configured to store the first PDU in afirst HARQ buffer associated with the first HARQ process; and inresponse to a determination being made to transmit the first PDU inassociation with the second HARQ process, move the first PDU from thefirst HARQ buffer to a second HARQ buffer associated with the secondHARQ. In another aspect, the buffer manager of the apparatus is furtherconfigured to move the second PDU from a MAC buffer to a second HARQbuffer associated with the second HARQ process in response to adetermination being made to transmit the second PDU in association withthe second HARQ process. In an aspect, the transmission determiner ofthe apparatus is configured to determine whether to transmit the firstPDU or the second PDU based at least in part on a difference intransmission time and/or a difference in size between the first explicitgrant and the second explicit grant.

FIG. 10 is a diagram illustrating an example of a hardwareimplementation for an apparatus employing a processing system. In someexamples, the processing system 1014 may be an example of a UE 115 or anetwork entity 220 described with reference to FIGS. 1-3. In thisexample, the processing system 1014 may be implemented with a busarchitecture, represented generally by the bus 1002. The bus 1002 mayinclude any number of interconnecting buses and bridges depending on thespecific application of the processing system 1014 and the overalldesign constraints. The bus 1002 links together various circuitsincluding one or more processors, represented generally by the processor1004, computer-readable media, represented generally by thecomputer-readable medium 1006, uplink transmission manager component201, or uplink grant manager component 211 (see FIG. 2A), which may beconfigured to carry out one or more methods or procedures describedherein.

In some instances, the communication management component 305 may beimplemented when processing system 1014 is used in a UE 115 or networkentity 220. In an aspect, uplink transmission manager component 201 andthe components therein may comprise hardware, software, or a combinationof hardware and software that may be configured to perform thefunctions, methodologies (e.g., method 400 of FIG. 4), or methodspresented in the present disclosure. Uplink grant manager component 211and the components therein may comprise hardware, software, or acombination of hardware and software that may be configured to performthe functions, methodologies (e.g., method 500 of FIG. 5), or methodspresented in the present disclosure.

The bus 1002 may also link various other circuits such as timingsources, peripherals, voltage regulators and power management circuits,which are well known in the art, and therefore, will not be describedany further. A bus interface 1008 provides an interface between the bus1002 and a transceiver 1010. The transceiver 1010 provides a means forcommunicating with various other apparatus over a transmission medium.Depending upon the nature of the apparatus, a user interface 1012 (e.g.,keypad, display, speaker, microphone, joystick) may also be provided.

The processor 1004 is responsible for managing the bus 1002 and generalprocessing, including the execution of software stored on thecomputer-readable medium 1006. The software, when executed by theprocessor 1004, causes the processing system 1014 to perform the variousfunctions described infra for any particular apparatus. Thecomputer-readable medium 1006 may also be used for storing data that ismanipulated by the processor 1004 when executing software. In someaspects, at least a portion of the functions, methodologies, or methodsassociated with the uplink transmission manager component 201 or uplinkgrant manager component 211 may be performed or implemented by theprocessor 1004 and/or the computer-readable medium 1006.

In some examples, the computer-readable medium 1006 may store code forwireless communications. The code may comprise instructions executableby a computer (e.g., processor 1004) for monitoring one or more wirelesschannels for one or more trigger conditions, for transmitting a probesignal over a first wireless channel of the one or more wirelesschannels to access a network entity when the one or more triggerconditions are met on the first wireless channel, wherein properties ofthe probe signal are based at least on a type of access with the networkentity; and for receiving a response signal from the network entity inresponse to the probe signal, the response signal including informationto enable access by the first wireless device.

Referring to FIG. 11, a Node B 1110 is in communication with a UE 1150and having aspects configured to manage cell update messages. In anaspect, the Node B 1110 may be an example of a network entity 220associated with core network 130 of FIGS. 2A and 2B, executing uplinkgrant manager component 211. In an aspect, the UE 1150 may be an exampleof UE 115 of FIGS. 1, 2A, and 2C, executing uplink transmission managercomponent 201. In the downlink communication, a transmit processor 1120may receive data from a data source 1112 and control signals from acontroller/processor 1140. The transmit processor 1120 provides varioussignal processing functions for the data and control signals, as well asreference signals (e.g., pilot signals). For example, the transmitprocessor 1120 may provide cyclic redundancy check (CRC) codes for errordetection, coding and interleaving to facilitate forward errorcorrection (FEC), mapping to signal constellations based on variousmodulation schemes (e.g., binary phase-shift keying (BPSK), quadraturephase-shift keying (QPSK), M-phase-shift keying (M-PSK), M-quadratureamplitude modulation (M-QAM), and the like), spreading with orthogonalvariable spreading factors (OVSF), and multiplying with scrambling codesto produce a series of symbols. Channel estimates from a channelprocessor 1144 may be used by a controller/processor 1140 to determinethe coding, modulation, spreading, and/or scrambling schemes for thetransmit processor 1120. These channel estimates may be derived from areference signal transmitted by the UE 1150 or from feedback from the UE1150. The symbols generated by the transmit processor 1120 are providedto a transmit frame processor 1130 to create a frame structure. Thetransmit frame processor 1130 creates this frame structure bymultiplexing the symbols with information from the controller/processor1140, resulting in a series of frames. The frames are then provided to atransmitter 1132, which provides various signal conditioning functionsincluding amplifying, filtering, and modulating the frames onto acarrier for downlink transmission over the wireless medium throughantenna 1134. The antenna 1134 may include one or more antennas, forexample, including beam steering bidirectional adaptive antenna arraysor other similar beam technologies.

At the UE 1150, a receiver 1154 receives the downlink transmissionthrough an antenna 1152 and processes the transmission to recover theinformation modulated onto the carrier. The information recovered by thereceiver 1154 is provided to a receive frame processor 1160, whichparses each frame, and provides information from the frames to a channelprocessor 1194 and the data, control, and reference signals to a receiveprocessor 1170. The receive processor 1170 then performs the inverse ofthe processing performed by the transmit processor 1120 in the Node B1110. More specifically, the receive processor 1170 descrambles anddispreads the symbols, and then determines the most likely signalconstellation points transmitted by the Node B 1110 based on themodulation scheme. These soft decisions may be based on channelestimates computed by the channel processor 1194. The soft decisions arethen decoded and de-interleaved to recover the data, control, andreference signals. The CRC codes are then checked to determine whetherthe frames were successfully decoded. The data carried by thesuccessfully decoded frames will then be provided to a data sink 1172,which represents applications running in the UE 1150 and/or various userinterfaces (e.g., display). Control signals carried by successfullydecoded frames will be provided to a controller/processor 1190. Whenframes are unsuccessfully decoded by the receive processor 1170, thecontroller/processor 1190 may also use an acknowledgement (ACK) and/ornegative acknowledgement (NACK) protocol to support retransmissionrequests for those frames.

In the uplink channel, data from a data source 1178 and control signalsfrom the controller/processor 1190 are provided to a transmit processor1180. The data source 1178 may represent applications running in the UE1150 and various user interfaces (e.g., keyboard). Similar to thefunctionality described in connection with the downlink transmission bythe Node B 1110, the transmit processor 1180 provides various signalprocessing functions including CRC codes, coding and interleaving tofacilitate FEC, mapping to signal constellations, spreading with OVSFs,and scrambling to produce a series of symbols. Channel estimates,derived by the channel processor 1194 from a reference signaltransmitted by the Node B 1110 or from feedback contained in themidamble transmitted by the Node B 1110, may be used to select theappropriate coding, modulation, spreading, and/or scrambling schemes.The symbols produced by the transmit processor 1180 will be provided toa transmit frame processor 1182 to create a frame structure. Thetransmit frame processor 1182 creates this frame structure bymultiplexing the symbols with information from the controller/processor1190, resulting in a series of frames. The frames are then provided to atransmitter 1156, which provides various signal conditioning functionsincluding amplification, filtering, and modulating the frames onto acarrier for uplink transmission over the wireless medium through theantenna 1152.

The uplink transmission is processed at the Node B 1110 in a mannersimilar to that described in connection with the receiver function atthe UE 1150. A receiver 1135 receives the uplink transmission throughthe antenna 1134 and processes the transmission to recover theinformation modulated onto the carrier. The information recovered by thereceiver 1135 is provided to a receive frame processor 1136, whichparses each frame, and provides information from the frames to thechannel processor 1144 and the data, control, and reference signals to areceive processor 1138. The receive processor 1138 performs the inverseof the processing performed by the transmit processor 1180 in the UE1150. The data and control signals carried by the successfully decodedframes may then be provided to a data sink 1139 and thecontroller/processor, respectively. If some of the frames wereunsuccessfully decoded by the receive processor, thecontroller/processor 1140 may also use an acknowledgement (ACK) and/ornegative acknowledgement (NACK) protocol to support retransmissionrequests for those frames.

The controller/processors 1140 and 1190 may be used to direct theoperation at the Node B 1110 and the UE 1150, respectively. For example,the controller/processors 1140 and 1190 may provide various functionsincluding timing, peripheral interfaces, voltage regulation, powermanagement, transmission management, and other control functions. Thecomputer readable media of memories 1142 and 1192 may store data andsoftware for the Node B 1110 and the UE 1150, respectively. Ascheduler/processor 1146 at the Node B 1110 may be used to allocateresources to the UEs and schedule downlink and/or uplink transmissionsfor the UEs. In an aspect, uplink grant manager component 211 maycommunicate with the controller/processors 1140 at the Node B 1110 formanaging uplink grants, and uplink transmission manager component 201may communicate with the controller/processors 1190 at the UE 1150 formanaging uplink transmissions.

The detailed description set forth above in connection with the appendeddrawings describes example embodiments and does not represent all theembodiments that may be implemented or that are within the scope of theclaims. The term “exemplary,” as used in this description, means“serving as an example, instance, or illustration,” and not “preferred”or “advantageous over other embodiments.” The detailed descriptionincludes specific details for the purpose of providing an understandingof the described techniques. These techniques, however, may be practicedwithout these specific details. In some instances, well-known structuresand devices are shown in block diagram form in order to avoid obscuringthe concepts of the described embodiments.

Information and signals may be represented using any of a variety ofdifferent technologies and techniques. For example, data, instructions,commands, information, signals, bits, symbols, and chips that may bereferenced throughout the above description may be represented byvoltages, currents, electromagnetic waves, magnetic fields or particles,optical fields or particles, or any combination thereof.

The various illustrative blocks and modules described in connection withthe disclosure herein may be implemented or performed with ageneral-purpose processor, a digital signal processor (DSP), an ASIC, anFPGA or other programmable logic device, discrete gate or transistorlogic, discrete hardware components, or any combination thereof designedto perform the functions described herein. A general-purpose processormay be a microprocessor, but in the alternative, the processor may beany conventional processor, controller, microcontroller, or statemachine. A processor may also be implemented as a combination ofcomputing devices (e.g., a combination of a DSP and a microprocessor,multiple microprocessors, one or more microprocessors in conjunctionwith a DSP core, or any other such configuration).

The functions described herein may be implemented in hardware, softwareexecuted by a processor, firmware, or any combination thereof. Ifimplemented in software executed by a processor, the functions may bestored on or transmitted over as one or more instructions or code on acomputer-readable medium. Other examples and implementations are withinthe scope of the disclosure and appended claims. For example, due to thenature of software, functions described above may be implemented usingsoftware executed by a processor, hardware, firmware, hardwiring, orcombinations of any of these. Features implementing functions may alsobe physically located at various positions, including being distributedsuch that portions of functions are implemented at different physicallocations. Also, as used herein, including in the claims, “or” as usedin a list of items (for example, a list of items prefaced by a phrasesuch as “at least one of” or “one or more of”) indicates an inclusivelist such that, for example, a list of at least one of A, B, or C meansA or B or C or AB or AC or BC or ABC (i.e., A and B and C).

Computer-readable media includes both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. A storage medium may be anyavailable medium that can be accessed by a general purpose or specialpurpose computer. By way of example, and not limitation,computer-readable media may comprise RAM, ROM, electrically erasableprogrammable read only memory (EEPROM), compact disk (CD) ROM or otheroptical disk storage, magnetic disk storage or other magnetic storagedevices, or any other medium that may be used to carry or store desiredprogram code means in the form of instructions or data structures andthat may be accessed by a general-purpose or special-purpose computer,or a general-purpose or special-purpose processor. Also, any connectionis properly termed a computer-readable medium. For example, if thesoftware is transmitted from a web site, server, or other remote sourceusing a coaxial cable, fiber optic cable, twisted pair, digitalsubscriber line (DSL), or wireless technologies such as infrared, radio,and microwave, then the coaxial cable, fiber optic cable, twisted pair,DSL, or wireless technologies such as infrared, radio, and microwave areincluded in the definition of medium. Disk and disc, as used herein,include CD, laser disc, optical disc, digital versatile disc (DVD),floppy disk and Blu-ray disc where disks usually reproduce datamagnetically, while discs reproduce data optically with lasers.Combinations of the above are also included within the scope ofcomputer-readable media.

The previous description of the disclosure is provided to enable aperson skilled in the art to make or use the disclosure. Variousmodifications to the disclosure will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other variations without departing from the scope of thedisclosure. Thus, the disclosure is not to be limited to the examplesand designs described herein but is to be accorded the broadest scopeconsistent with the principles and novel features disclosed herein.

Techniques described herein may be used for various wirelesscommunications systems such as code division multiple access (CDMA),time division multiple access (TDMA), frequency division multiple access(FDMA), orthogonal frequency division multiple access (OFDMA), singlecarrier frequency division multiple access (SC-FDMA), and other systems.The terms “system” and “network” are often used interchangeably. A CDMAsystem may implement a radio technology such as CDMA2000, UniversalTerrestrial Radio Access (UTRA), etc. CDMA2000 covers IS-2000, IS-95,and IS-856 standards. IS-2000 Releases 0 and A are commonly referred toas CDMA2000 1×, 1×, etc. IS-856 (TIA-856) is commonly referred to asCDMA2000 1×EV-DO, High Rate Packet Data (HRPD), etc. UTRA includesWideband CDMA (WCDMA) and other variants of CDMA. A TDMA system mayimplement a radio technology such as Global System for MobileCommunications (GSM). An OFDMA system may implement a radio technologysuch as Ultra Mobile Broadband (UMB), Evolved UTRA (E-UTRA), IEEE 802.11(Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM, etc. UTRA andE-UTRA are part of Universal Mobile Telecommunications system (UMTS).3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A) are new releasesof Universal Mobile Telecommunications System (UMTS) that use E-UTRA.UTRA, E-UTRA, UMTS, LTE, LTE-A, and Global System for MobileCommunications (GSM) are described in documents from an organizationnamed “3rd Generation Partnership Project” (3GPP). CDMA2000 and UMB aredescribed in documents from an organization named “3rd GenerationPartnership Project 2” (3GPP2). The techniques described herein may beused for the systems and radio technologies mentioned above as well asother systems and radio technologies. The description above, however,describes an LTE system for purposes of example, and LTE terminology isused in much of the description above, although the techniques areapplicable beyond LTE applications.

What is claimed is:
 1. A method for managing uplink transmissions in alicense-assisted access (LAA) wireless communication system, comprising:receiving a first explicit uplink grant for transmission of a firstprotocol data unit (PDU) associated with a first Hybrid Automatic RepeatRequest (HARQ) process; receiving a second explicit uplink grant fortransmission of a second PDU associated with a second HARQ process, thesecond explicit uplink grant being received subsequent to the firstexplicit uplink grant; performing a first clear channel assessment (CCA)in response to the first explicit uplink grant in a first time slot;performing a second CCA in response to the second explicit uplink grantin a second time slot; and determining, in response to the first CCAfailing and the second CCA succeeding, whether to transmit the first PDUor the second PDU in a time slot subsequent to the second time slot overan unlicensed spectrum or a shared spectrum.
 2. The method of claim 1,further comprising: storing the first PDU in a first HARQ bufferassociated with the first HARQ process; and in response to adetermination to transmit the first PDU in association with the secondHARQ process, moving the first PDU from the first HARQ buffer to asecond HARQ buffer associated with the second HARQ process.
 3. Themethod of claim 2, further comprising determining to transmit the firstPDU based on at least one of a time duration between receipt of thefirst explicit uplink grant and the second explicit uplink grant beingless than or equal to a threshold time, or a second grant size of thesecond explicit uplink grant being larger than or equal to a size of thefirst PDU.
 4. The method of claim 2, further comprising clearing thefirst HARQ buffer in response to the moving of the first PDU to thesecond HARQ buffer.
 5. The method of claim 1, further comprising, inresponse to a determination to transmit the second PDU in associationwith the second HARQ process, moving the second PDU from a MAC buffer toa second HARQ buffer associated with the second HARQ process.
 6. Themethod of claim 5, further comprising determining to transmit the secondPDU based on at least one of a time duration between receipt of thefirst explicit uplink grant and the second explicit uplink grant beinggreater than a threshold time, and a second grant size of the secondexplicit uplink grant being smaller than a size of the first PDU.
 7. Themethod of claim 1, wherein determining whether to transmit the first PDUor the second PDU in the time slot subsequent to the second time slotover the unlicensed spectrum or the shared spectrum is based at least inpart on a difference in transmission time and/or a difference in sizebetween the first explicit grant and the second explicit grant.
 8. Themethod of claim 1, wherein receiving the first explicit uplink grant orthe second explicit uplink grant comprises receiving from a primarycell.
 9. The method of claim 1, further comprising transmitting adetermined one of the first PDU or the second PDU over the unlicensedspectrum or the shared spectrum.
 10. The method of claim 9, whereindetermining whether to transmit the first PDU or the second PDU furtherincludes determining to transmit the first PDU and at least a portion ofthe second PDU.
 11. A user equipment (UE), comprising: a memory; atransceiver, and one or more processors operatively coupled with thememory and the transceiver, the one or more processors configured to:receive, via the transceiver, a first explicit uplink grant fortransmission of a first protocol data unit (PDU) associated with a firstHybrid Automatic Repeat Request (HARQ) process; receive, via thetransceiver, a second explicit uplink grant for transmission of a secondPDU associated with a second HARQ process, the second explicit uplinkgrant being received subsequent to the first explicit uplink grant;perform a first clear channel assessment (CCA) in response to the firstexplicit uplink grant in a first time slot; perform a second CCA inresponse to the second explicit uplink grant in a second time slot; anddetermine, in response to the first CCA failing and the second CCAsucceeding, whether to transmit the first PDU or the second PDU in atime slot subsequent to the second time slot over an unlicensed spectrumor a shared spectrum.
 12. The UE of claim 11, wherein the one or moreprocessors are further configured to: store the first PDU in a firstHARQ buffer associated with the first HARQ process; and in response to adetermination to transmit the first PDU in association with the secondHARQ process, move the first PDU from the first HARQ buffer to a secondHARQ buffer associated with the second HARQ process.
 13. The UE of claim12, wherein the one or more processors are further configured todetermine to transmit the first PDU based on at least one of a timeduration between receipt of the first explicit uplink grant and thesecond explicit uplink grant being less than or equal to a thresholdtime, or a second grant size of the second explicit uplink grant beinglarger than or equal to a size of the first PDU.
 14. The UE of claim 12,wherein the one or more processors are further configured to clear thefirst HARQ buffer in response to the moving of the first PDU to thesecond HARQ buffer.
 15. The UE of claim 11, wherein the one or moreprocessors are further configured to, in response to a determination totransmit the second PDU in association with the second HARQ process,move the second PDU from a MAC buffer to a second HARQ buffer associatedwith the second HARQ process.
 16. The UE of claim 15, wherein the one ormore processors are further configured to determine to transmit thesecond PDU based on at least one of a time duration between receipt ofthe first explicit uplink grant and the second explicit uplink grantbeing greater than a threshold time, and a second grant size of thesecond explicit uplink grant being smaller than a size of the first PDU.17. The UE of claim 11, wherein determining whether to transmit thefirst PDU or the second PDU in the time slot subsequent to the secondtime slot over the unlicensed spectrum or the shared spectrum is basedat least in part on a difference in transmission time and/or adifference in size between the first explicit grant and the secondexplicit grant.
 18. The UE of claim 11, wherein receiving the firstexplicit uplink grant or the second explicit uplink grant comprisesreceiving from a primary cell.
 19. The UE of claim 11, wherein the oneor more processors are further configured to transmit a determined oneof the first PDU or the second PDU over the unlicensed spectrum or theshared spectrum.
 20. The UE of claim 11, wherein determining whether totransmit the first PDU or the second PDU further includes determining totransmit the first PDU and at least a portion of the second PDU.
 21. Anon-transitory computer readable medium having instructions storedtherein that, in response to execution by one or more processors, causethe one or more processors to: receive a first explicit uplink grant fortransmission of a first protocol data unit (PDU) associated with a firstHybrid Automatic Repeat Request (HARQ) process; receive a secondexplicit uplink grant for transmission of a second PDU associated with asecond HARQ process, the second explicit uplink grant being receivedsubsequent to the first explicit uplink grant; perform a first clearchannel assessment (CCA) in response to the first explicit uplink grantin a first time slot; perform a second CCA in response to the secondexplicit uplink grant in a second time slot; and determine, in responseto the first CCA failing and the second CCA succeeding, whether totransmit the first PDU or the second PDU in a time slot subsequent tothe second time slot over an unlicensed spectrum or a shared spectrum.22. The non-transitory computer readable medium of claim 21, furthercomprising instructions that, in response to execution by the one ormore processors, cause the one or more processors to: store the firstPDU in a first HARQ buffer associated with the first HARQ process; andin response to a determination to transmit the first PDU in associationwith the second HARQ process, move the first PDU from the first HARQbuffer to a second HARQ buffer associated with the second HARQ process.23. The non-transitory computer readable medium of claim 22, furthercomprising instructions that cause the one or more processors todetermine to transmit the first PDU based on at least one of a timeduration between receipt of the first explicit uplink grant and thesecond explicit uplink grant being less than or equal to a thresholdtime, or a second grant size of the second explicit uplink grant beinglarger than or equal to a size of the first PDU.
 24. The non-transitorycomputer readable medium of claim 22, further comprising instructionsthat, in response to execution by the one or more processors, cause theone or more processors to clear the first HARQ buffer in response to themoving of the first PDU to the second HARQ buffer.
 25. Thenon-transitory computer readable medium of claim 21, further comprisinginstructions that, in response to execution by the one or moreprocessors, cause the one or more processors to, in response to adetermination to transmit the second PDU in association with the secondHARQ process, move the second PDU from a MAC buffer to a second HARQbuffer associated with the second HARQ process.
 26. The non-transitorycomputer readable medium of claim 25, further comprising instructionsthat cause the one or more processors to determine to transmit thesecond PDU based on at least one of a time duration between receipt ofthe first explicit uplink grant and the second explicit uplink grantbeing greater than a threshold time, and a second grant size of thesecond explicit uplink grant being smaller than a size of the first PDU.27. The non-transitory computer readable medium of claim 21, wherein theinstructions that cause the one or more processors to determine whetherto transmit the first PDU or the second PDU in the time slot subsequentto the second time slot over the unlicensed spectrum or the sharedspectrum comprise instructions that cause the one or more processors todetermine based at least in part on a difference in transmission timeand/or a difference in size between the first explicit grant and thesecond explicit grant.
 28. The non-transitory computer readable mediumof claim 21, wherein the instructions that cause the one or moreprocessors to receive the first or the second explicit uplink grantcomprise instructions that cause the one or more processors to receivethe first or the second explicit uplink grant from a primary cell. 29.The non-transitory computer readable medium of claim 21, furthercomprising instructions that, in response to execution by the one ormore processors, cause the one or more processors to transmit adetermined one of the first PDU or the second PDU over the unlicensedspectrum or the shared spectrum.
 30. The non-transitory computerreadable medium of claim 21, wherein the instructions that cause the oneor more processors to determine whether to transmit the first PDU or thesecond PDU comprise instructions that cause the one or more processorsto determine to transmit the first PDU and at least a portion of thesecond PDU.
 31. A user equipment (UE), comprising: means for receiving afirst explicit uplink grant for transmission of a first protocol dataunit (PDU) associated with a first Hybrid Automatic Repeat Request(HARQ) process; means for receiving a second explicit uplink grant fortransmission of a second PDU associated with a second HARQ process, thesecond explicit uplink grant being received subsequent to the firstexplicit uplink grant; means for performing a first clear channelassessment (CCA) in response to the first explicit uplink grant in afirst time slot; means for performing a second CCA in response to thesecond explicit uplink grant in a second time slot; and means fordetermining, if the first CCA fails and the second CCA succeeds, whetherto transmit the first PDU or the second PDU in a time slot subsequent tothe second time slot over an unlicensed spectrum or a shared spectrum.32. The UE of claim 31, further comprising: means for storing the firstPDU in a first HARQ buffer associated with the first HARQ process; andmeans for moving, in response to a determination being made to transmitthe first PDU in association with the second HARQ process, the first PDUfrom the first HARQ buffer to a second HARQ buffer associated with thesecond HARQ process.
 33. The UE of claim 32, further comprising meansfor determining to transmit the first PDU based on at least one of atime duration between receipt of the first explicit uplink grant and thesecond explicit uplink grant being less than or equal to a thresholdtime, or a second grant size of the second explicit uplink grant beinglarger than or equal to a size of the first PDU.
 34. The UE of claim 32,further comprising means for clearing the first HARQ buffer in responseto the moving of the first PDU to the second HARQ buffer.
 35. The UE ofclaim 31, further comprising means for moving, in response to adetermination to transmit the second PDU in association with the secondHARQ process, the second PDU from a MAC buffer to a second HARQ bufferassociated with the second HARQ process.
 36. The UE of claim 35, furthercomprising means for determining to transmit the second PDU based on atleast one of a time duration between receipt of the first explicituplink grant and the second explicit uplink grant being greater than athreshold time, and a second grant size of the second explicit uplinkgrant being smaller than a size of the first PDU.
 37. The UE of claim31, wherein means for determining whether to transmit the first PDU orthe second PDU in the time slot subsequent to the second time slot overthe unlicensed spectrum or the shared spectrum comprises means fordetermining based at least in part on a difference in transmission timeand/or a difference in size between the first explicit grant and thesecond explicit grant.
 38. The UE of claim 31, wherein means forreceiving the first explicit uplink grant or the second explicit uplinkgrant comprises means for receiving from a primary cell.
 39. The UE ofclaim 31, further comprising means for transmitting a determined one ofthe first PDU or the second PDU over the unlicensed spectrum or theshared spectrum.
 40. The UE of claim 31, wherein means for determiningwhether to transmit the first PDU or the second PDU comprises means fordetermining to transmit the first PDU and at least a portion of thesecond PDU.